What source are you getting this from?
Victor Stenger, philosopher and physicist, explains it.
Cosmological inflation seems to be eternal the way it is theorised. Although new inflation is classically rolling down the potential, quantum fluctuations can sometimes bring it back up to previous levels. These regions in which the
inflaton fluctuates upwards expand much faster than regions in which the
inflaton has a lower potential energy, and tend to dominate in terms of physical volume. This steady state, which first developed by Vilenkin,
[62] is called "eternal inflation". It has been shown that any inflationary theory with an unbounded potential is eternal.
[63] It is a popular belief among physicists that this steady state cannot continue forever into the past.
[64][65][66] The inflationary spacetime, which is similar to
de Sitter space, is incomplete without a contracting region. However, unlike de Sitter space, fluctuations in a contracting inflationary space will collapse to form a
gravitational singularity, a point where densities become infinite. Therefore, it is necessary to have a theory for the universe's initial conditions. Linde, however, believes inflation may be past eternal.
[wiki] (Not that I understand what the heck they're talking about, but it sounds like they think it may well be eternal)
Can you list one of these?
I understand that there are events at the quantum level that physicists say are not caused. I am not a physicist myself, so don't ask me to explain it. Maybe one will happen along.
